Fabrication of sub-100 nm IDT SAW devices on insulating, semiconducting and conductive substrates

This work describes the electron-beam (e-beam) lithography process developed to manufacture nano interdigital transducers (IDTs) to be used in high frequency (GHz) surface acoustic wave (SAW) applications. The combination of electron-beam (e-beam) lithography and lift-off process is shown to be effective in fabricating well-defined IDT finger patterns with a line width below 100 nm with a good yield. Working with insulating piezoelectric substrates brings about e-beam deflection. It is also shown how a very thin organic anti-static layer works well in avoiding this charge accumulation during e-beam lithography on the resist layer. However, the use of this anti-static layer is not required with the insulating piezoelectric layer laying on a semiconducting substrate such as highly doped silicon. The effect of the e-beam dose on a number of different layers (of insulating, insulating on semiconducting, semiconducting, and conductive natures) is provided. Among other advantages, the use of reduced e-beam doses increases the manufacturing time. The principal aim of this work is to explain the interrelation among e-beam dose, substrate nature and IDT structure. An extensive study of the e-beam lithography of long IDT-fingers is provided, in a wide variety of electrode widths, electrode numbers and electrode pitches. It is worthy to highlight that this work shows the influence of the e-beam dose on five substrates of different conductive natur

Optimization of AlN thin layers on diamond substrates for high frequency SAW resonators

AlN/diamond heterostructures are very promising for high frequency surface acoustic wave (SAW) resonators. In their design, the thickness of the piezoelectric film is one of the key parameters. On the other hand, the film material quality and, hence, the device performance, also depend on that thickness. In this work, polished microcrystalline diamond substrates have been used to deposit AlN films by reactive sputtering, from 150 nm up to 3 μm thick. A high degree of the c-axis orientation has been obtained in all cases. SAW one port resonators at high frequency have been fabricated on these films with a proper combination of the film thickness and transducer size

Graphene radio: Detecting radiowaves with a single atom sheet

We present the experimental evidence of RF demodulation by a graphene monolayer embedded in a coplanar structure. The demodulator was tested in the frequency range from 100 MHz to 25 GHz using amplitude modulated input signals. An input power of 0 dBm (1 mW) was used which is the typical power emitted for short range wireless communication systems, such as Bluetooth. The graphene demodulator exhibits good signal response in the frequency range associated to industrial, scientific and medical (ISM) radio band (2.4 GHz)

DATA COMPRESSION AND PANORAMIC IMAGES FORMATION IN UAV MILITARY TV-MONITORING SYSTEM

UAVs are unmanned aerial vehicles. UAVs with qualities of robots are called "drones" and are used mostly for acquisition and transmission of TV image for observation missions in enemy territories or guarding of objects and large land areas. TV images acquired by these drones are converted into compressed data and then transmitted to the ground via radio - communications. If the monitored area is large or the observed object is big, then more drones buy pieces from the total image. The paper shows the results of the analysis of experimental data compression standard methods and Method of panoramic images formation in the conditions of initial frames with low detail is offered. Method saves perspective of base frame

Graphene-like metallic-on-silicon field effect transistor

In this manuscript, we present a field effect transistor with a channel consisting of a two-dimensional electron gas located at the interface between an ultrathin metallic film of Ni and a p-type Si(111) substrate. We have demonstrated that the two-dimensional electron gas channel is modulated by the gate voltage. The dependence of the drain current on the drain voltage has no saturation region, similar to a field effect transistor based on graphene. However, the transport in this transistor is not ambipolar, as in graphene, but unipolar

A 3D Smith Chart based on the Riemann Sphere for Active and Passive Microwave Circuits

“© © 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.”This letter proposes a spherical 3-D Smith Chart suitable for representing both active and passive microwave circuits. Using the mathematical concept of the Riemann sphere, the extended reflection coefficient plane is transformed into the surface of the unit sphere. Since the proposed Smith Chart compiles the whole complex plane, all possible loads are included. A simple graphic tool is thus obtained that successfully unifies active and passive circuits. In addition, lossy lines with complex characteristic impedances can also be represented. The letter presents the 3-D Smith Chart, provides its main governing equations, and also enumerates its more important properties. © 2011 IEEE.This work was supported in part by the POSDRU ID 7713 European Project and by the Ministerio de Ciencia e Innovacion, Spanish Government under Research Project TEC2010-21520-C04-01.Muller, AA.; Soto Pacheco, P.; Dascalu, D.; Neculoiu, D.; Boria Esbert, VE. (2011). A 3D Smith Chart based on the Riemann Sphere for Active and Passive Microwave Circuits. IEEE Microwave and Wireless Components Letters. 21(6):286-288. https://doi.org/10.1109/LMWC.2011.2132697S28628821

Cardioprotection in coronary artery bypass graft surgery: the impact of remote ischemic preconditioning on modulating LOX-1 and SOD-1 to counteract oxidative stress

BackgroundCoronary artery bypass grafting (CABG) is frequently used to treat severe coronary artery disease (CAD), but it can lead to increased oxidative stress and inflammation, worsening patient outcomes. Remote ischemic preconditioning (RIPC) has been suggested as a potential strategy to protect against these effects by modulating oxidative stress and inflammatory responses, though its impact on specific biomarkers requires further investigation. This study aims to assess the effects of remote ischemic preconditioning on inflammation markers and oxidative stress in patients with severe CAD undergoing coronary artery bypass grafting.MethodsWe conducted a case-control study involving 80 patients with severe coronary artery disease (CAD) scheduled for coronary artery bypass grafting (CABG). Fifty percent of these patients received ischemic preconditioning prior to surgery. Plasma levels of Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) and Superoxide dismutase-1 (SOD-1) levels were measured in all individuals using the ELISA method at three important time points: before surgery (visit 1 or V1), immediately post-operatively (visit 2 or V2), and one week post-operatively (visit 3 or V3).ResultsWe enrolled 80 patients, of which 40 were assigned to the studied group receiving remote ischemic preconditioning (RIPC) and 40 to the control group. There were no statistically significant differences between the groups regarding baseline, clinical, or operative characteristics. RIPC treatment significantly reduced plasma levels of Lectin-like oxidized low-density lipoprotein (LDL) receptor-1 (LOX-1) (p < 0.05) as well as significantly increasing total values of Superoxide dismutase-1 (SOD-1) (p < 0.05, respectively). There were notable differences between the studied and control groups at V2 and V3. The studied group had higher SOD-1 levels (p < 0.05) and significantly lower LOX-1 levels at both time points (p < 0.05).ConclusionThe significant changes in plasma levels of both LOX-1 and SOD-1 observed in this study strongly suggest that remote ischemic preconditioning (RIPC) plays an important role in reducing oxidative stress and enhancing the antioxidative status of patients. This is evidenced by the marked decrease in LOX-1 levels, alongside a corresponding increase in SOD-1 levels, indicating that RIPC may contribute to improved cardioprotection through these mechanisms

Comprobación de la presencia de probióticos en productos de uso oral

El objetivo principal de esta investigación fue comprobar la presencia de probióticos en productos de uso oral, comercializados en las diferentes farmacias ubicadas en la Colonia Médica de San Salvador, en las presentaciones de cápsulas, comprimidos masticables y sobres. Para la recolección de la muestra se utilizó una hoja de cotejo, que se aplicó para la identificación de los probióticos comercializados en cada una de las 16 farmacias en estudio, obteniendo un total de 24 muestras. Se realizó una descripción de cada uno de los productos con la normativa de etiquetado Reglamento Técnico Centroamericano RTCA 11.01.02:04 Productos Farmacéuticos. Etiquetado de Productos Farmacéuticos para uso Humano. Así mismo un recuento en placa de bacterias ácido lácticas, también una identificación de los microrganismos tanto a nivel macroscópico como microscópico de las presentaciones de cápsulas, comprimidos masticables y sobres, se comparó con el estándar de referencia Lactobacillus rhamnosus. Obteniéndose los siguientes resultados: para las muestras de cápsulas su crecimiento en placa fue de 1.5x103 UFC/mL, las de comprimidos masticables su crecimiento fue de 1.3x103 UFC/mL y las de sobres de 1.9x103 UFC/mL. En las tres presentaciones el crecimiento en placa fue inferior al rango que establece la Organización de las Naciones Unidas para la Agricultura y la Organización Mundial de la Salud (FAO/OMS) de 106 a 109 UFC. Para ser considerado como probiótico y ejercer un efecto positivo para el consumidor. Se recomiendan nuevas investigaciones con diferentes marcas y presentaciones de probióticos, para poder confirmar si contiene la cantidad que especifica en los productos. La investigación de llevó a cabo en el Laboratorio de Microbiología del Centro de Investigaciones y Desarrollo en Salud (CENSALUD) de la Universidad de El Salvador, durante el periodo de 2017 al 2019

High performance thin film bulk acoustic resonator covered with carbon nanotubes

This letter presents experimental results concerning a thin film bulk acoustic wave resonator realized on a thin GaN membrane and covered with a thin film of double walled carbon nanotube mixture. The quality factor was measured before and after the coating of the resonator with the nanotube thin film. The quality factor has increased more than ten times when the resonator was coated with nanotubes, due to their high elasticity modulus and low density, which confers a much higher acoustic impedance of the resonator electrodes and thus confines much better the longitudinal acoustic standing waves inside the resonator

TRUNK WITH FOLDING CROSSBARS, PATENT OSIM – RO NR. 130559/2019 PROPOSED FOR INSTALLATION ON THE DACIA – DUSTER CAR

The work presents a manner of implementation of an existing Romanian patent (OSIM - Ro Patent no. 130559/2019 which refers to a car trunk with folding crossbars), for its adaptation to the Dacia-DUSTER car, as a SMART trunk. The novelty element is that the trunk is designed in such a way that it can fold / hide inside the longitudinal bars when it is not used (leading to fuel savings), and respectively, it can be extended by folding to be put in a working position, when it becomes active. In addition, the trunk has possibilities of adjustment depending on the types / dimensions of the luggage transported and is integrated more harmoniously with the shape of the car's body, compared to the existing universa